Lapping apparatus



L. DAY ETAL Dec. 28, 1965 LAPP-ING APPARATUS 3 Sheets-Sheet 1 Filed Jan. 30, 1964 a m K m m m w E H W27 m E E WM m m5 T gm 5 Dec. 28, 1965 L. DAY ETAL 3,225,492

LAPPING APPARATUS Filed Jan. 50, 1964 3 Sheets-Sheet 2 THE/R 17704575) Dec. 28, 1965 L. DAY ETAL 3,225,492

LAPPING APPARATUS Filed Jan. 30, 1964 3 Sheets-Sheet 3 TORS 77727 firm/Mix it tes act 3,225,492 LAPPING APPARATUS Lawrence Day and Joseph Dohrick, Qhicago, and Arthur Kay, Evanston, lii., assignors to Spitfire Tool is: Machine (30., Erie, Chicago, ill, a corporation of Illinois Filed Jan. 30, 1964, Ser. No. 341,178 3 Claims. (Cl. 51-3) Another and equally important object of our invention is the provision of an arrangement for oscillating the workpiece transversely of a lap plate while such workpiece rotates in coplanar relation with respect to such lap plate beneath a non-rotatable lap plate, the weight of which is disposed upon the workpiece for effectively holding the same in lapping position within the workholder and upon the lap plate.

Another object of the invention is the provision of an arrangement for eccentrically rotating the workholder of the apparatus independently of eccentric rotation of the lap plate, thus to enable rotation of the workholder and lap plate in the same or opposite directions and at the same or different speeds, thereby to produce the finest micro-inch finish.

A further object of our invention resides in the novel and simple arrangement which facilitates re-dressing the lapping members in a most expeditious and efficient manner resulting in a considerable saving in operating time.

Other objects will appear hereinafter.

The invention consists in the novel combination and arrangement of parts to be hereinafter described and claimed.

The invention will be best understood by reference to the accompanying drawings showing the preferred form of construction, and in which:

FIG. 1 is a fragmentary perspective view of the invention;

FIG. 2 is a fragmentary perspective of the invention similar to FIG. 1, but showing the pressure disc disposed upon the work;

FIG. 3 is a cross sectional detail view taken substantially on line 3-3 of FIG. 2;

FIG. 4 is a top plan view of a workholder disc and ring embodied in the invention;

FIG. 5 is a perspective view of a workpiece of the type which is lapped by the invention.

The present invention may be used in connection with the lapping apparatus shown in our United States Patent No. 3,032,937 dated May 8, 1962. The apparatus there disclosed includes a base it) within which and at the top thereof rotates a lapping table 37 rotated in any suitable manner. Extending in an upward direction from the base it) is a standard or post 11 comprising sections 12 and 12'. The section 12 is adjustable vertically with respect to the section 12. The means and manner of this adjustment constitutes no part of the present invention. The structure for accomplishing the same may be that shown and described in our patent above referred to. The section 12 has an integral laterally extending arm 13 which adjustably supports the motor mounting plate 14, the adjustment being accomplished by any suitable means including a hand wheel 15. The manner and means of adjusting the plate 1 2- does not constitute any part of the present invention, but is merely shown and described for illustrative purposes.

The plate 14 carries a reversible motor 16, the operating ing shaft (not shown) of which, through the medium of a train of gears arranged in a housing 17, is connected to a driven shaft 18. This shaft 18 extends through and is keyed to a sleeve 18 by a screw 17. The drive sleeve 13' rotatably fits into a depending main stationary tube 19 which is fixed to and carried by the arm 13 and movable therewith. A drive shaft 19 has one end portion movably inserted in the lower end portion of the sleeve 18 (FIG. 3).

Formed in the drive sleeve 18' is an elongated slot A screw stud 14' is threaded into shaft 19 to provide for limited longitudinal movement of the shaft 19" relative to the drive sleeve 18'. The shaft 19' is journalled in suitable bearings 26 press-fitted into the tube 19. The tube 19 has a reduced portion 21 which is fixedly secured in a cap 22 in any suitable manner.

The cap 22 is connected by means of bolts 23 to a pressure lapping plate 24. This plate on its under surface 25 has a circumferential relatively flat rib 26 which, as will be hereinafter apparent and as shown in the drawings (FIG. 3), engages the top surface of the work to be lapped when such plate is in its lowered position.

The reduced portion 21 is mounted in a suitable universal bearing 25 of the construction shown in FIG. 3 or any other approved construction such as will permit plate 24 to be self-adjustable in a horizontal plane upon the workpieces. Such bearing is mounted in a central opening 22 formed in the cap 22. The cap 22 rotates about such reduced portion 21 in the manner and for the reasons hereinafter set forth.

The lower end portion 27 of the shaft 19' projects into a bore 28 formed eccentrically in a disc 39 centrally arranged in a disc-like workholder 39. The workholder is free to rotate about the disc 31 in a manner presently set forth. A transverse slot 29 is formed in the disc 34 (PEG. 3). The workholder 31, as best seen in FIGS. 1 and 4, provides a plurality of elongated radially extending slots 32 spaced circumferentially with respect to each other. The slots 32 may be arranged in pairs, with each pair offset radially with respect to each other.

An intermediate lapping plate 33 has opposite sides which are of like construction and configuration. Each side provides a circumferentially extending relatively fiat lapping rib 34 adapted to engage the cylindrical surfaces of the workpieces. The lapping plate 33 is arranged in a retainer ring 35 (FIG. 3). The ring 35 is formed of lapping material, such as cast iron or the like. The lapping plate 33 is keyed to the ring 35 for rotation therewith by means of a slot and pin connection 36 (FIG. 3). The lapping plate 33 operates upon the rotatable lapping table heretofore referred to.

Formed centrally in the lapping plate 33 is an opening 38 into which is rotata-bly positioned a pilot stud 3? formed as an integral part of the disc 34 The disc 36 rotatably fits into an opening 46) formed in the workholder 31 and offset with respect to the central axis thereof. The workholder 31 is properly spaced above the lapping plate 33 by removable shims 42.

Carried by the shaft 19' at its lower end 27 is a pin 43 which removably engages in the slot 29 of the disc 30. lnterposed between the lower bearing of the bearings 20 and the pin 43 is an expansion spring 44 which operates to yieldably move the shaft 19' downwardly to project the pin 43 into the slot 29 upon registration of such pin with such slot.

Mounted on the base ltl is a reversible motor 45, the shaft of which through a train of gears within a housing 46 is connected to a driven shaft 47. The'shaft 47 carries a grooved pulley 48 operatively engaging a belt 49 which operates in a groove 54 formed in the ring 35. By this arrangement, rotation of the ring 35 imparts rotation to the lapping plate 33 about its vertical axis upon the lapping table 37 while the latter is rotated about its vertical axis.

Carried by the cap 22 is a vertical pin 51 which engages in a slot 52 formed in a bifurcated block 53 (FIG. 1) secured to the non-rotatable tube 19 by a draw bolt 58 which releasably clamps the block 53 to the tube 19. The pin 51 and block 53 serve to hold the pressure lapping plate 24 from rotating with the workholder 31 while the pressure lapping plate 24 is in its lowered position upon the work.

In operation, the arm 13 through the medium of the section 12 and in a manner such as disclosed in our aforementioned patent, is elevated a sufficient distance to expose the workholder 31 to permit placing the workpieces 54 in the slots 32. A suitable abrading material is placed upon the surfaces of the workpieces 54. The pressure lapping plate 24 is then lowered into position with the fiat lapping rib 26 thereof in contact with the workpieces 54. One of the functions of the pressure plate 24 is that of applying pressure to the workpieces during lapping operation so as to produce a high quality lapped surface on the workpiece. The motor 45 is caused to operate to rotate the lap plate 33, through rotation of the ring 35. The speed of rotation of the ring may be the same or different from that of the lapping table 37 depending upon the type of lap desired. The parts are permitted to continue to rotate until the desired finish is obtained on the workpieces 54.

The upward longitudinal movement of the shaft 15 within the tube 19 is permitted by virtue of the elongated slot 15 within which the screw stud 14 operates. When the tube 19 and the lapping plate 24 carried thereby are lowered into position upon the workholder 31, the pin '43 may in the first instance be out of alignment with the slot '29. Upon rotation of the shaft 19, the pin 43 being rotatable with the shaft 19, will rotate into registration with the slot 29 and by the spring 44 be projected into the latter, thus providing connection between the shaft 19 and the disc 39 whereby rotation of the disc 30 will impart eccentric movement to the workholder '31 relative to the lapping plates 24 and 33. Such operation reciprocates the workpiece with respect to the stationary pressure plate 24 (the same being restrained from rotation during lapping operation) and the intermediate lapping plate 33.

As is apparent from the foregoing construction and the operation of the same described hereinafter, the workpieces 54 are subjected to a multiplicity of movements which enable us to lap the cylindrical workpieces to a substantial micro finish.

Essentially the workpieces 54 rotate about their own long axes and circumferentially with respect to the lapping plates 24 and 33 and also during these movements reciprocate radially with respect to such lapping plates.

The axial and circumferential rotation of the workpieces 54 result by reason of their contact with the nonrotatable lapping plate 24 and the rotatable lapping plate 33, the rotation of the latter, with the cooperation of the non-rotatable lapping plate 24, imparting both axial rotation and circumferential rotation to the workpieces 54. Reciprocal movement of the workpieces 54- with respect to the lapping plates 24 and 33 is brought about by reciprocal movement of the workholder 31 with respect to the lapping plates 24 and 33 by reason of the eccentric connection between the workholder 31 and the driving shaft 19'.

After a predetermined lapping operation, it becomes necessary to re-dress the lapping surfaces of not only the plates 24 and 33 but also the revolving lapping table 37. By the construction hereinbefore set forth, these lapping plates may be re-dressed effectively and efiiciently with a minimum degree of loss in operating time and without removal (as is done in prior art devices) of the lapping table which is generally of substantial size and weight. This is accomplished in the following manner:

To redress the lapping plate 24 and lapping table 37, the workholder 31 and lapping plate 33 must be removed from the operative position shown in FIG. 3. This we accomplish as follows: The arm 13 is elevated by upward movement of the section 12 in a manner such as described in our aforesaid patent. Such upward movement of the arm 13 will elevate the tube w and the lapping plate 24 carried thereby a sufiicient distance above the workholder 31 to disengage the pin 43 from the slot 29 and to permit manual removal of the workholder 31 and the lapping plate 33. After such removal of these elements, the arm 13 is lowered to engage the lapping plate 24 into contact with the revolving lapping table 37. The shaft 19' Will move upwardly within the tube 19 when the lapping plate 24 engages the lapping table 37. This is allowed by reason of the engagement of the lower end portion of the shaft 19' with the revolving lapping table 37, at which time the shaft 19 will be moved longitudinally of the tube 19 against the action of the spring 44-. The lapping plate 24 is thus disposed into dressing contact with respect to the revolving lapping table 37. The upward longitudinal movement of the shaft 19' is permitted by reason of the provision of the slot 15' into which the stud screw 14 projects.

The next step in this operation is to release the plate 24 for rotation, it being hereinbefore pointed out that the plate 24 is held against rotation by the block 53 and pin 51 during lapping of the workpieces (FIG. 2). When released for rotation, the plate 24 is caused to rotate within the ring 35 by reason of its frictional contact with the rotatable lapping table 37. To permit such rotation of the lapping plate 24 the draw bolt 53' is loosened to release the clamping connection between the block 53 and the tube 19, to free the block 53 and the lapping plate 24 for rotation relative to the tube 19. Rotation of the lapping plate 24- about its axis combined with rotation of the revolving lapping table 37 about its axis, will effectively dress the lapping plate 24, the lapping table 37 having been dressed by the ring 35.

As the lapping plate 33 is reversible, when one side has become worn or requires dressing, it may be reversed to dispose such side in contact with the revolving lapping table 37 and be thereby re-dressed.

By the foregoing arrangement, the cumbersome and expensive operation of entirely removing the revolving lapping table 37 from the machine and placing the same upon another lapping machine for re-dressing purposes, as is the present practice in the art, is eliminated. In our construction it is not necessary to remove the lapping table 37 for dressing purposes, nor is it necessary to remove the lapping plate 24.

While we have illustrated and described the preferred form of construction for carrying our invention into effect, this is capable of variation and modification without departing from the spirit of the invention. We therefore do not wish to be limited to the precise details of construction set forth, but desire to avail ourselves of such variations and modifications as come within the scope of the appended claims.

Having thus described our invention, what we claim as new and desire to protect by Letters Patent is:

1. An apparatus for lapping cylindrical workpieces comprising (a) a rotatable retainer ring mounted for rotation upon a supporting plate,

(b) a disc-like lapping plate arranged in said ring and having a centrally located opening,

(c) slot and pin means for keying said lapping plate to said ring for rotation therewith,

(d) means for rotating said ring relative to its center axis,

(e) a disc-like workholder arranged above said lapping plate and having a plurality of slots formed therein to receive said workpieces to be lapped by said lap ping plate, said workholder having a centrally (i) means for rotating said ring,

(j) a work'holder disposed between said pressure lapping plate and said intermediate lapping plate,

(k) a vertically extending arm extending upwardly from and supported on said base at one side of said pressure lapping plate,

(1) means connecting said horizontally extending arm to said vertical arm for adjustment relative to the cated opening, 5 latter whereby said horizontally extending arm and (f) an eccentric rotatably positioned in said opening of said pressure lapping plate may be positioned above said workholder, said eccentric having a stud prosaid ring to permit manual removal of said workjecting into a centrally located opening formed in holder and said intermediate lapping plate from withsaid lapping plate, in said ring to expose said lapping table to said pres- (zg) reversible motor means, 10 sure lapping plate for dressing engagement with said (h) a shaft rotated by said motor means, lapping table when said workholder and the inter- (i) a slot and pin connection between said shaft and mediate lapping plate have been manually removed said eccentric for rotating the latter to effect reciprofrom said ring and the pressure lapping plate is lowcation of said workholder with respect to said lapered from said elevated position into engagement ping plate, with said lapping table,

(3') and a vertically movable non-rotatable pressure disc a p ng member Ca r by Said tu e and propositioned in said retainer ring and bearing upon Vided at B Side With a Vertically eXtendillg 510i, workpieces positioned in said workholder. means for clamping Said Clamping 11161111361" I0 Said 2. The lapping apparatus defined by claim 1 wherein tube,

said plurality of slots is circumferentially arranged and in (0) and a pin carried by said pressure lapping plate pairs with each pair alternately offset radially with reand P j g into Said Slot Pr v nt r tatiOn 0f e t t h th said pressure lapping plate relative to said tube when 3 A l i hi comprising said pressure lapping plate is lowered into lapping a base, contact with work within said workholder,

(b) a horizontally rotatably supported lapping table 5 (P) Said clamping means being loosened to free i Within said base atthe top th f clamping member from holding said pressure plate (C) a retainer ring Supported on Said lapping table, from rotation by action of the rotation of the lap- (d) a vertically adjustable horizontally extending arm Pmg tab1e when sald P P PP Plate 13 m above Said base, dressing engagement with said lapping table.

(e) a tube fixed to and depending from said arm and located axially with respect to said ring, References C'ted by the Exammer (f) a pressure lapping plate carried by the lower end UNITED STATES PATENTS of the tube for positioning within said ring, 1,605,161 11/1926 Bl d 51 11g X (g) an intermediate lapping plate Within said ring and 3? 1,610,984 12/1926 Van Keuren 51118 X beneath said pressure lapping plate and supported 1,937,459 11/ 1933 Hill 51-3 by said lapping table within said ring, 1,963,884 6/1934 Budd 513 (h) means keying said intermediate lapping plate to 3,03 ,9 7 1962 Day et al. 51128 said ring for rotation therewith, 9 12/1964 Roshong 51-131 X ROBERT c. RIORDON, Primary Examiner.

LESTER M. SWINGLE, Examiner.

J. A. MATHEWS, Assistant Examiner. 

1. AN APPARATUS FOR LAPPING CYLINDRICAL WORKPIECES COMPRISING (A)A ROTATABLE RETAINER RING MOUNTED FOR ROTATION UPON A SUPPORTING PLATE. (B) A DISC-LIKE LAPPING PLATE ARRANGED IN SAID RING SAID HAVING A CENTRALLY LOCATED OPENING, (C) SLOT, AND PIN MEANS FOR KEYING SAID LAPPING PLATE TO SAID RING FOR ROTATION THEREWITH, (D) MEANS FOR ROTATING SAID RING RELATIVE TO ITS CENTER AXIS, (E) A DISC-LIKE WORKHOLDER ARRANGED ABOVE SAID LAPPING PLATE AND HAVING A PLURALITY OF SLOTS FORMED THEREIN TO RECEIVE SAID WORKPIECES TO BE LAPPED BY SAID LAPPING PLATE, SAID WORKHOLDER HAVING A CENTRALLY LOCATED OPENING, (F) AN ECCENTRIC ROTATABLY POSITIONED IN SAID OPENING OF SAID WORKHOLDER, SAID ECCENTRIC HVING A STUD PROJECTING INTO A CENTRALLY LOCATED OPENING FORMED IN SAID LAPPING PLATE, (G) REVERSIBLE MOTOR MEANS, (H) A SHAFT ROTATED BY SAID MOTOR MENAS, (I) A SLOT AND PIN CONNECTION BETWEEN SAID SHAFT AND SAID ECCENTRIC FOR ROTATING THE LATTER TO EFFECT RECIPROCATION OF SAID WORKHOLDER WITH RESPECT TO SAID LAPPING PLATE, (J) AN A VERTICALLY MOVABLE NON-ROTATABLE PRESSURE DISC POSITIONED IN SAID RETAINER RING AND BEARING UPONG WORKPIECES POSITIONED IN SAID WORKHOLDER. 